Change field value and submit node with a custom button - drupal

Question

I am attempting to write a module that adds a button to a node type that, when pressed, will change a value of a field in that node and submit the changes. Everything seems to be working, as the button appears correctly and the node submits when it's pressed, but the value of the field remains unchanged. I feel like I'm missing something obvious.
<?php
function iu_buttons_node_view($node, $view_mode, $langcode) {
if ($node->type == 'billing_entry') {
if ($node->field_status['und'][0]['value'] == 'open') {
$form = drupal_get_form('submit_button_form');
$node->content['submit_button'] = $form;
}
}
}
function submit_button_form($form, &$form_submit) {
$form['submit'] = array(
'#type' => 'button',
'#value' => ('Submit'),
'#submit' => array('submit_button_form_submit'),
);
return $form;
}
function submit_button_form_submit($form, &$form_state) {
$node->field_status['und'][0]['value']['#value'] = 'submitted';
}
It's probably worth noting that the field I'm trying to change is a select list. Should I be using a different function than hook_form_submit?

Answer 1

I am assuming you are writing this code in a custom module named iu_buttons and you want to display this button in the node page, not in the node edit form.
In this case, the problem is that you never saved the node in your submit function. Here is a version of your submit function that will save the node.
function submit_button_form_submit($form, &$form_state) {
$node = menu_get_object(); //get the current node
$node->field_status['und'][0]['value']['#value'] = 'submitted';
node_save($node); // save the changed node
}
I think you may be interested in saving only the field, without the need to save the whole node. In this case, you might use the following:
function submit_button_form_submit($form, &$form_state){
$node = new stdClass(); // Create empty object
$node->nid = intval(args(1)); // Include the nid so that Drupal saves the new value to the correct node
$node->field_status['und'][0]['value']['#value'] = 'submitted';
field_attach_update('node', $node); // Save the field
}